July 18, 2019

# Rethinking Probability

“The gambler, the quantum physicist and the juror all reason about probabilities: the probability of winning, of a radioactive atom decaying, of a defendant’s guilt. But despite their ubiquity, experts dispute just what probabilities are. This leads to disagreements on how to reason about, and with, probabilities – disagreements that our cognitive biases can exacerbate, such as our tendency to ignore evidence that runs counter to a hypothesis we favour. Clarifying the nature of probability, then, can help to improve our reasoning.

Three popular theories analyse probabilities as either frequencies, propensities or degrees of belief. Suppose I tell you that a coin has a 50 per cent probability of landing heads up. These theories, respectively, say that this is:

The frequency with which that coin lands heads;
The propensity, or tendency, that the coin’s physical characteristics give it to land heads;
How confident I am that it lands heads.
But each of these interpretations faces problems. Consider the following case:

Adam flips a fair coin that self-destructs after being tossed four times. Adam’s friends Beth, Charles and Dave are present, but blindfolded. After the fourth flip, Beth says: ‘The probability that the coin landed heads the first time is 50 per cent.’
Adam then tells his friends that the coin landed heads three times out of four. Charles says: ‘The probability that the coin landed heads the first time is 75 per cent.’
Dave, despite having the same information as Charles, says: ‘I disagree. The probability that the coin landed heads the first time is 60 per cent.’”

## World

### The End of British Soft Power

"The likely successor to British Prime Minister Theresa May, Boris Johnson, has plans to subsume the government department overseeing development aid into the foreign office, effectively eliminating it. That will destroy a post-Brexit United..."

## United States

### Predicting the Unpredictable President

"Gerard Baker, editor-at-large at the Wall Street Journal (no reflexively anti-Trump publication) recently wrote a piece decrying Donald Trump and his foreign policy as a fount of erratic unpredictability. This essay will give the counter view...."

## Israel

### Will Ilhan Omar Be Allowed Into Israel?

"On Wednesday, Congresswoman Ilhan Omar announced that she will be visiting Israel and the Palestinian territories in the coming weeks. Omar will be accompanied by Rep. Rashida Tlaib. The two freshman congresswomen have become a focal point of..."

## Hollywood

### Why Is Netflix Obsessed with Adam Sandler?

"Netflix may have lost US subscribers for the first time since it began making its own shows, but that didn't stop the streaming giant from dropping new figures about how many people are sucked into its Adam Sandler vortex. (Spoiler: More than..."

## Money

### Get Ready for the Four-Day Work Week

"A few years ago, Amy Balliett, CEO of a Seattle-based design and marketing firm, noticed that as the work week slogged on, her employees’ energy and productivity wilted. “That would slump to such an extent that the same task on Monday would..."

## Tech

### No, FaceApp Isn't an Evil Russian Plot

"Over the last few days the #faceappchallenge has taken over social media. This “challenge” involves downloading a selfie-editing tool called FaceApp and using one of its filters to digitally age your face. You then post the photo of your wizened..."

## Culture

### Understanding the American Lawn

"Although there are plenty of irrational aspects to life in modern America, few rival the odd fixation on lawns. Fertilizing, mowing, watering — these are all-American activities that, on their face, seem reasonable enough. But to spend hundreds..."

## Books

### Learning How to Listen

"Can a book change the way we think? I don’t mean that in the sense of a reader’s opinion or ideology shifting—of course the right literary work can do that. But can a book rewire the brain itself, literally changing the way one particular mind..."

## Family

### For Sibling Battles, Be a Sportscaster, Not a Referee

"It’s our job to let kids know we see and hear them, but we’re not necessarily going to solve siblings’ conflicts for them (or else they never get the practice). When squabbles start, imagine you’re a sportscaster and describe what you see in..."

## Food

### Dating: A Great Way to Get a Free Meal

"Magali Trejo-Martinez, a 22-year-old living in Salem, Oregon, recently went on a date that was rather uninspiring. “I had dinner, had a couple margaritas, and then went home,” is how she recapped the evening. This outcome wasn’t entirely..."

## Science

### The Aesthetic Achievement of the Moon Landing

"The first lunar landing was many things — a D-Day-like feat of planning and logistics, a testament to the power of man's will, an ostensible propaganda coup for NATO. It was also, I think, one of the most misunderstood events in the history of..."

## Judaism

### Unpacking Bernie's Jewishness

"THE FIRST TIME Bernie Sanders ran for president, he didn’t talk much about being Jewish. In fact, he didn’t talk much about himself at all. His 2016 primary campaign, like his whole political career, was relentlessly focused on one topic: income..."